The present invention relates generally to fluid flow, and more particularly to a flow control system and to a valve for controlling a fluid flow.
Conventional flow control systems include servo-controlled valves for controlling a fluid flow in a conduit. Conventional valves include needle type valves and flapper type valves wherein movement of a needle or a flapper inside the conduit adjusts the flow cross-sectional area between a full flow state and a zero flow state. Some flow control applications, such as kidney dialysis machines and intravenous drug delivery systems, require all parts of the valve in contact with the fluid flow to be clean of debris or other contaminants (such as chemical or biological contaminants) prior to each use. This requires a new valve or cleaning of the needle/flapper and other fluid-contacting portions of the valve prior to each use.
What is needed is an improved flow control system and an improved valve for controlling a fluid flow.
In a first expression of an embodiment of the invention, a valve, for controlling a fluid flow in a flexible conduit, includes a stationary member and a movable member. The stationary member is adapted to support a first region of the outer surface of the flexible conduit. The movable member is movable to compressingly contact a second region of the outer surface of the flexible conduit, wherein the second region substantially opposes the first region enabling the movable member to compress the flexible conduit to adjust the flow cross-sectional area of the flexible conduit.
In a second expression of an embodiment of the invention, a flow control system includes a flexible conduit, a valve, and a controller. The valve includes a stationary member and a movable member. The stationary member supports a first region of the outer surface of the flexible conduit. The movable member is movable to compressingly contact a second region of the outer surface of the flexible conduit, wherein the second region substantially opposes the first region enabling the movable member to compress the flexible conduit to adjust the flow cross-sectional area of the flexible conduit. The controller is operatively connected to the movable member for controllably moving the movable member.
In a third expression of an embodiment of the invention, a valve, for controlling a fluid flow in a flexible conduit, includes a stationary member, a first wheel, and a second wheel. The stationary member is adapted to support a first region of the outer surface of the flexible conduit. The first wheel has a first central axis and is drivingly rotatable about the first central axis. The second wheel has a second central axis, is attached to and projects beyond the first wheel, and is freely rotatable about the second central axis. The second central axis is spaced apart from the first central axis. Driving rotation of the first wheel moves the second wheel in a substantially circular arc to compressingly contact a second region of the outer surface of the flexible conduit. The second region substantially opposes the first region enabling the second wheel to compress the flexible conduit to adjust the flow cross-sectional area of the flexible conduit.
In a fourth expression of an embodiment of the invention, a flow control system includes a flexible conduit, a valve, and a controller. The valve includes a stationary member, a first wheel, and a second wheel. The stationary member supports a first region of the outer surface of the flexible conduit. The first wheel has a first central axis and is drivingly rotatable about the first central axis. The second wheel has a second central axis, is attached to and projects beyond the first wheel, and is freely rotatable about the second central axis. The second central axis is spaced apart from the first central axis. Driving rotation of the first wheel moves the second wheel in a substantially circular arc to compressingly contact a second region of the outer surface of the flexible conduit. The second region substantially opposes the first region enabling the second wheel to compress the flexible conduit to adjust the flow cross-sectional area of the flexible conduit. The controller is operatively connected to the first wheel for drivingly rotating the first wheel about the first central axis.
In a first broader expression of an embodiment of the invention, a valve, for controlling a fluid flow in a flexible conduit having an outer surface and a flow cross-sectional area, includes a movable member movable to compressingly contact the outer surface of the flexible conduit to adjust the flow cross-sectional area of the flexible conduit.
In a second broader expression of an embodiment of the invention, a flow control system includes a flexible conduit, a valve, and a controller. The flexible conduit has an outer surface, has an inner surface for containing a fluid flow, and has a flow cross-sectional area. The valve includes a movable member movable to compressingly contact the outer surface of the flexible conduit to adjust the flow cross-sectional area of the flexible conduit. The controller is operatively connected to the movable member for controllably moving the movable member.
Several benefits and advantages are derived from one or more of the expressions of an embodiment of the invention. Having the flow cross-sectional area be adjusted by compressingly contacting an outer surface of a flexible conduit containing the fluid flow prevents the valve components from ever coming into contact with the fluid flow. Since only the flexible conduit comes into contact with the fluid flow, only the flexible conduit is replaced or cleaned in flow control applications, such as kidney dialysis machines and intravenous drug delivery systems, requiring all parts in contact with the fluid flow to be clean of debris or other contaminants (such as chemical or biological contaminants) prior to each use. The free rotation of the second wheel about the second central axis allows the second wheel, despite its circular arc motion, to compressingly contact the flexible conduit without longitudinally moving the flexible conduit as can be appreciated by those skilled in the art.